PTL 1 and 2 report an oxazole compound having specific inhibitory activity against phosphodiesterase 4 (PDE4) and a method for producing the oxazole compound. PDE4 is predominant in inflammatory cells. Inhibition of PDE4 increases intracellular cAMP levels, and increased cAMP levels down-regulate inflammatory response through expression regulation of TNF-α, IL-23, or other inflammatory cytokines. Increases in cAMP levels also increase anti-inflammatory cytokines, such as IL-10. Thus, the oxazole compound is thought to be suitable for use as an anti-inflammatory agent. For example, the oxazole compound is thought to be useful to reduce or eliminate eczema or dermatitis, including atopic dermatitis.
However, so far there has been no ointment that stably contains an oxazole compound having specific inhibitory activity against PDE4 and that can be efficiently absorbed into the skin.